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218933-98-3

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218933-98-3 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 218933-98-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,1,8,9,3 and 3 respectively; the second part has 2 digits, 9 and 8 respectively.
Calculate Digit Verification of CAS Registry Number 218933-98:
(8*2)+(7*1)+(6*8)+(5*9)+(4*3)+(3*3)+(2*9)+(1*8)=163
163 % 10 = 3
So 218933-98-3 is a valid CAS Registry Number.

218933-98-3Relevant articles and documents

Asymmetric synthesis of α-substituted β-amino sulfones by aza-Michael addition to alkenyl sulfones and subsequent α-alkylation

Enders, Dieter,Müller, Stephan Frank,Raabe, Gerhard,Runsink, Jan

, p. 879 - 892 (2007/10/03)

The aza-Michael addition of enantiopure 1-aminopyrrolidines to (E)- alkenyl sulfones in the presence of a catalytic amount of ytterbium trifluoromethanesulfonate [Yb(OTf)3] yields β-hydrazino sulfones in moderate to good yields and with diastereoselectivities of up to 98%. The latter undergo reductive N-N bond cleavage with BH3 · THF and, after N- protection with Boc2O or benzyl bromide, afford N-protected β-amino sulfones with moderate to high enantiomeric excesses (ee = 42 to ≥96%) without racemization. Subsequent α-alkylation of the N,N-dibenzyl protected β-amino sulfones with various electrophiles yields α-alkyl-β-amino sulfones in excellent yields (88-97%) with high diastereomeric (de ≥96 to ≥98%) and enantiomeric purity (ee = 94 to ≥96%). The absolute configuration of the new stereogenic centre was determined by X-ray structural analysis and confirmed by NMR spectroscopy (NOE experiments). Possible reaction mechanisms for the conjugate addition and α-alkylation are presented.

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